Novel two-dimensional semiconductor SnP3: high stability, tunable bandgaps and high carrier mobility explored using first-principles calculations

Abstract

We propose a novel two-dimensional crystal based on layered bulk metallic SnP₃ using first-principles calculations. The obtained low cleavage energy of monolayer and bilayer SnP₃ implies the possibility of their exfoliation from layered bulk SnP₃ experimentally. Monolayer and bilayer SnP₃ are structurally stable with 0.72 eV and 1.02 eV indirect band gaps, respectively, at the HSE06 functional level. Tunable bandgaps can be achieved by strain engineering. With a compressive strain of 4%, the valence band maximum of bilayer SnP₃ varies from the high symmetry point K to point Γ, resulting in transformation from an indirect to a direct semiconductor. Analogous to phosphorene, remarkably high carrier mobilities are predicted for monolayer SnP₃, which is several times higher than that of monolayer GeP₃. The hole mobilities of bilayer SnP₃ can reach as high as 10⁴ cm² V⁻¹ s⁻¹. Moreover, an excellent absorption coefficient in the range of solar spectrum was predicted. These results qualify monolayer and bilayer SnP₃ as promising novel 2D materials for applications in microelectronics, optoelectronics and field-effect transistors.